The present invention relates to vehicles which include an internal combustion engine and, more specifically, to starters used with such vehicles.
Conventional internal combustion engine vehicles utilize a starter when initially starting the internal combustion engine. Typically, a battery powers an electrical starter motor which turns a flywheel and thereby turns the engine over. The starter provides torque to the engine for a brief period of time until the engine starts to operate normally and no longer needs assistance.
In a conventional vehicle, the starter will be used when initially starting the engine and the engine will continue to run until the operator intentionally stops the engine. Recently, however, many vehicles have begun employing a stop-start system where the electronic control unit (“ECU”) of the vehicle intentionally stops the engine based upon the operating conditions of the vehicle and subsequently restarts the engine based upon operating conditions of the vehicle. This stopping and starting of the engine occurs without the operator of the vehicle actively stopping or starting the engine.
Hybrid vehicles often employ a stop-start system to temporarily stop the operation of the internal combustion engine when the vehicle is brought to a stop or when the forward propulsion of the vehicle can be entirely provided by an electric traction motor. It is also becoming increasingly desirable to provide a stop-start system in non-hybrid vehicles which are entirely reliant upon an internal combustion engine for propulsion. In such non-hybrid vehicles, the stop-start system will typically only stop the engine when the brake is being applied and the vehicle is being brought to a stop or when the vehicle is stopped. The use of a stop-start system in such vehicles will, thereby, typically turn off the engine when the vehicle is stopped and in an idling situation. By automatically turning off the engine in such idling situations, the stop-start system not only enhances fuel-economy but also reduces emissions.
In many vehicles, the starter used to initially start the engine is also used when the ECU automatically restarts the engine after stopping the engine as a part of a stop-start system. The start-stop system may have “change-of-mind” capabilities wherein it is able to restart the engine very shortly after the engine was stopped and the fly-wheel is still inertially rotating. In such starter-based stop-start systems, the starter will typically have a pinion gear that is capable of engaging a rotating ring gear that is coupled with a flywheel to thereby restart the engine. Such starters may have what is referred to as a synchronized design wherein the rotational speeds of both the pinion gear and the ring gear are sensed and the pinion gear is engaged only when the speeds of the two gears are synchronized. A solenoid is typically used to move the pinion gear into and out of engagement with the ring gear.
In such starter-based stop-start systems, the starter is subjected to greater demands than a conventional starter in a vehicle without a stop-start system. While it is always undesirable to have a vehicle starter fail, in a conventional vehicle without a stop-start system, if the starter fails, the vehicle will generally be stranded at a location where the operator had intentionally parked the vehicle and stopped the engine. In a vehicle having a stop-start system, if the starter fails after the ECU had automatically stopped the engine as a function of the stop-start system, the vehicle has a greater possibility of being stranded in a highly inconvenient location such as a left turn lane at a busy intersection.